The ordinance, the brainchild of City Councilman Arnie Fielkow, was designed to shed light on the sometimes-opaque process by which city contracts are awarded. Nagin has argued that it is both impractical and a legal violation to force the meetings at which contractors are ranked to be public.

Fielkow, who issued statement Monday saying he was "disappointed though not surprised" by the mayor's action, will ask his colleagues to override the the veto at the council's next meeting Thursday. It takes five votes to override a veto.

Under current policy, would-be vendors are evaluated by a committee composed of the chief administrative officer, the director of the relevant department and, for contracts larger than $150,000, a third person from outside City Hall, nominated by a civic or business organization and appointed by Nagin. The committee meets in private and makes a recommendation to the mayor.

The new law would require those meetings to be held in public.

In the wake of the law's passage, Nagin had hinted that he might either ignore the law or take the matter to court. That may still be a possibility, as the council's previous unanimous vote on the matter seems to make a veto override likely.

He also said the law would accomplish little. "I'm done. I have implemented transparency," Nagin told a television station, dismissing the demand for public meetings as "nothing of any substance."